JPS6235039B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to delayed detonators, and more particularly to electric and non-electric detonators having a detonator of an exothermic combustible composition adjacent to a detonator of a heat-sensitive explosive. Delayed blasting technology improves rock fragmentation and displacement, provides better control of vibration, noise and rock splatter, lowers the powder factor, and improves rock fragmentation and displacement in underground and surface blasting operations.
It is widely practiced as a means to reduce the cost of detonation. Short-time or millisecond delayed detonators (e.g.
Detonators with a nominal delayed firing time of approximately 1000 ms or less) as well as long (normal) delayed detonators (e.g., with a nominal delayed firing time of greater than approximately 1000 ms) are used as needed for various detonation requirements. have been developed so far. Today, millisecond MS delayed detonators are the most commonly used detonators for quarrying, open pit mining and construction projects, and they are also used in underground mines for multiple row slabbing.
slabbing) blasting, stope blasting and other multiple rows of holes are free face
It is used for mining blasting, which collapses until it becomes stale. In general, MS delayed blasts move the rock farther away from its front due to the interaction between successive perforations that are ignited at shorter delay intervals than long delayed blasts. The nominal interval between delay times for a series of detonators in a commercial series is often as short as 25 milliseconds for lower-delay-period MS detonators; Long delay firing times can be up to 100 milliseconds for MS detonators, and up to about 500-600 milliseconds for long delay detonators. An important requirement for consecutive delayed detonations, especially for MS delayed detonations, is that the detonation times of a number of detonators of the same detonation rating be as uniform as possible without variation from one detonator to the other. Variation from the nominal value of the delayed firing time of a group of detonators with the same designated nominal delayed firing time means that the ignition interval between two adjacent detonators at any given delayed firing time will not be reduced to 8 milliseconds or less. It is desirable that the level is such that it does not occur. This means that the maximum variation allowed is ±8 ms for a 25 ms delay interval series detonator, ±21 ms for a 50 ms series detonator, and ±46 ms for a 100 ms series detonator. It means to become. Without good uniformity, it is difficult to obtain the desired fracture, vibration reduction, etc. that would be expected from the delayed pattern. In a delayed detonator, the delay interval, i.e., the time that elapses from the application of electrical or impact energy to the detonation of the detonator, is the interval between the ignition system and the detonator of the heat-sensitive explosive from the exothermic combustible composition. This is achieved by intervening a time delay drug. The delay interval is determined by the burning speed of the time delay medicine and the length of the cylindrical time delay medicine. In some detonators, the delay charge is loaded directly onto the point charge in the detonator barrel without the use of an enveloping element, but normally the delay charge is loaded as described in, for example, U.S. Pat. Figure 1) and 3021786
As shown in FIG. 2, it is housed inside a thick-walled, rigid carrier tube. The use of carrier tubes allows for smaller charges (i.e. charge weight per unit length).
This allows the delay charge to last longer (gives a longer delay time), and the total weight of the delay charge is accordingly reduced, so there is no risk of rupturing the detonator barrel or having a detrimental effect on the delay time. This is desirable because it eliminates the risk of causing harm. Extended drug carriers previously known in the art are mostly thick-walled metal (usually lead) tubing. However, the above-mentioned US Pat. No. 2,999,460 describes that the thick-walled carrier shown in FIG. 1 is, for example, a lead or plastic tube. Additionally, U.S. Patent 2,771,033 describes a core of a time-prolonging drug composition surrounded by a flexible textile sheath, and U.S. Pat. A protractor core surrounded by a covered envelope is described. In the present invention, in order from the closed end side, (a) an explosive composition [e.g., granular pentaerythritol tetranitrate (PETN) press-fitted] into a tubular metal outer cylinder whose one end is integrally closed; (b) a spotting charge consisting of a heat-sensitive explosive composition (e.g., lead azide); (c) a delay charge consisting of an exothermic combustible composition (e.g., a boron/red lead mixture); d) To provide an improvement in a delayed detonator which houses an igniter for delayed charge ignition. This improvement includes a layer of polyolefin or polyfluorocarbon, preferably at least about 0.5 mm thick, between the delay charge and the inner wall of the tubular metal barrel, and a point explosive in the charge of the tubular metal barrel. It consists of making it into a form that substantially prevents the infiltration of the drug into the time-prolonging drug. In a preferred embodiment of the invention, a barrier layer (e.g. of polyolefin or polyfluorocarbon) is provided between the time delay charge and the ignition charge so that the interface between the two is confined to a narrow area near the central axis of the tubular metal barrel. layer) forms the trigger charge in such a way as to prevent it from penetrating into the delay charge. In this embodiment, one end is an open end and the other end is a closure with an axial orifice extending therethrough, the closure being nested within a tubular metal barrel adjacent to the trigger charge. It is particularly preferred to house the protractor in a molded tubular polyolefin or polyfluorocarbon capsule. In another embodiment, the time delay charge is contained within a polyolefin or polyfluorocarbon tubing, and the spot charge is contained to such an extent that the spot charge substantially penetrates into the time delay charge when said tube is press-fitted thereon. Make the powder into a sufficiently compacted form so that it is not disturbed. The preferred delayed detonator of the present invention further includes a tubular rigid metal capsule nested within the polyolefin or polyfluorocarbon delayed drug containing tube or capsule. The rigid metal capsule has an open end at one end and a closed end with an axial orifice extending therethrough, the closed end of the capsule being adjacent to the delay charge and the open end preferably being connected to the igniter of the detonator. They are facing each other. Hereinafter, the present invention will be explained in detail with reference to the drawings. In Figure 1, 1 is a metal outer cylinder whose one end is integrally closed, 2 is an additive made of a granular explosive composition, 3 is a spot explosive made of a granular heat-sensitive explosive composition, and 4 is a granular exothermic combustion a time-prolonging drug consisting of a sexual composition;
Reference numeral 5 denotes a tubular capsule made of polyolefin or polyfluorocarbon that is accommodated inside the outer cylinder 1 by a sliding fit. The capsule 5 has an open end 6 at one end and a closed end 7 provided with an axial orifice 8 at the other end. The capsule 5 is a containment device or carrier for the delay charge 4, the side walls of which are polyolefin or polyfluorocarbon layers interposed between the delay charge 4 and the inner wall of the barrel 1, and its closed end 7 above the trigger charge 3. It is arranged in contact with this and acts as a barrier layer between the trigger charge 3 and the delay charge 4. Due to the axial orifice 8, a small axial interface 9 exists between the chemicals 3 and 4. A metal tubular capsule 10 is housed inside the capsule 5 in a sliding fit therewith, and the capsule 10 also has an open end 11 at one end and a closed end 12 provided with an axial orifice 13 at the other end. It's getting old. The capsule 10 has inside the capsule 5,
The closed end 12 is accommodated so as to rest directly on the time delay medicine 4. The closed end 11 faces an igniter 14 which contains a heat-sensitive igniter composition 1.
5. Consists of a pair of leg wires 16 and a high resistance bridge wire 17. The ignition charge 15 is contained within a plastic ignition cup 18. Place the outer cylinder 1 so that the grooved rubber stopper 19 covers the ignition powder 15.
The leg wire 16 is firmly fitted into the open end of the outer cylinder 1 to form a water-resistant closing part, and also serves to securely place the tip of the leg line 16 inside the outer cylinder 1. Example 1 The detonator shown in FIG. 1 of the attached drawings was manufactured as follows. The outer tube 1 was a standard detonator outer tube, for example, a 5052 series aluminum alloy outer tube with a length of 5.486 cm, an outer diameter of 0.73 cm, and an inner diameter of 0.66 cm. Additive 2 is
It consists of 0.49g of PETN, which is put into the outer cylinder 1.
It was pressed in using a sharp press pin with a force of 1220 to 1335 Newtons. Spot explosive 3 is an 85/15 mixture of dextrin-treated lead azide and coarse dinitrocresol lead salt.
The mixture (weight ratio) was 0.17 g, and this mixture was loaded into the outer cylinder 1 and press-fitted with a flat pin with a force of 1335 Newtons. Capsule 5 is 2.16 cm long and has an outer diameter of
It was made of high-density polyethylene with a diameter of 6.5 mm and an inner diameter of 5.3 mm, and the diameter of the axial orifice 8 was 1.3 mm. The capsule 5 is pressed into the barrel 1 with a force of 890 Newtons by an axially truncated pin shaped to prevent the point explosive 3 from entering the interior of the capsule 5 through the orifice 8. did. A time delay drug 4 is loosely loaded into a capsule 5, which is a mixture of boron and red lead grained with a polysulfide rubber, which controls the amount of time delay drug (and hence its length). The boron content of the mixtures was varied depending on the delay time to be achieved. The capsule 10 made of industrial bronze has a length of 11.9 mm.
It had an outer diameter of 0.561 cm and a wall thickness of 0.5 mm. The diameter of the axial orifice 13 was 2.8 mm. capsule 10
was seated in Capsule 5 at 1290 Newtons. The components of the ignition device 14 include an ignition cup 18 made of plastic (for example, polyethylene), a heat-sensitive igniter 15 granulated with polysulfide rubber (in this case, 0.27 g of a 2/98 boron/lead mixture). ), and two legs 16 of metal (copper or iron) insulated with plastic, the exposed ends of the legs 16 having a diameter embedded in the pyrotechnic charge.
It was connected to bridge wire 17 with a resistance of 0.0396 mm and 1.00 ohm. The ignition cup 18 was seated on top of the capsule 5. The above detonators were manufactured with nine different delay times. Each detonator contained a delay charge selected to provide a different nominal delay time increasing by 25 or 50 milliseconds from the shortest delay time. 25 detonators were selected from the lot of detonators produced for each delay time.
The actual delayed firing time was tested by igniting in air at 27°C. The results were as shown in Table 1 below.

[Table] Control experiment A detonator (nominal delayed firing time:
200 milliseconds), the detonator barrel 1 exploded when it was ignited. This is thought to be caused by the gas generated by the decomposition of the plastic. Example 2 Designated stage numbers 3, 7 and 9 as described in Example 1
A delayed detonator was tested for delayed firing time when ignited at 21°C in air and 27°C in water. Each stage of detonators was tested under both of these two conditions. The results are shown in the following table, along with the results obtained when prior art stage number 3 and stage 9 delayed detonators were tested under the same conditions. The test was performed 10 times under each condition for each stage. In the prior art detonator, the polyethylene capsule 5 was omitted.

[Table] Example 3 The detonator described in Example 1 having the structure shown in FIG. 1 was modified as shown in FIG. 2. This modification allows the capsule 5 to be connected to a polyolefin or polyfluorocarbon tube 20, in this case a polyethylene tube member (total length 1.8 mm) connected to two butts.
cm, outer diameter 0.64 cm, inner diameter 0.54 cm). The pressing force used to load the dot explosive 3, the tube body 20, and the capsule 10 into the outer cylinder 1 was the same as the press force used to load the dot explosive 3, capsule 5, and capsule 10, respectively, in Example 1. It was hot. When the 15 detonators with designated stage number 6 obtained in this way are ignited at 10°C, the average delay time is 202 milliseconds (σ = 8), and when the 15 detonators with the same stage number are ignited at 27°C. is 198
It was milliseconds (σ = 5.7). The prior art detonator with the same stage number (same number of test pieces) without the carrier of delay charge 4 had an average delay time of 187 milliseconds (σ = 9) when ignited at 10°C.
It took 174 milliseconds (σ=9) to ignite at 27°C. In other words, the time difference between these two temperatures is
13 milliseconds, whereas with the delayed detonator of the present invention, this difference is only 4 milliseconds. A prior art detonator (same test number) with a metal carrier for the delay charge 4 and with an electric match ignition device instead of the device 14 shown in FIG.
The average delay time was 213 ms (σ = 11) when ignited at 10°C, and 206 ms (σ = 11) when ignited at 27°C.
=9) (time difference of 7 milliseconds). The examples described above demonstrate good uniformity and predictability of the delayed firing time of the delayed detonator of the present invention when ignited under certain conditions, such that the delayed firing time of the detonator is less than that of a conventional detonator. shows that it is not significantly affected by the surrounding environment (temperature and medium density). A time delay charge carrier made of polyolefin or polyfluorocarbon provides a better fit between the time delay charge carrier and the metal barrel (thus a better sealing of the spot charge), as well as on the explosive spot charge. It is also advantageous to eliminate the friction-related hazards associated with fitting a metal delay charge carrier into a metal detonator barrel. Additionally, one of the beneficial effects of polyolefin or polyfluorocarbon carriers on delay time is that the delay time is less variable due to changes in ambient temperature or medium (eg, air or water). A time delay drug is an exothermic combustible composition, e.g.
Temperatures can reach temperatures as high as 100 degrees Celsius. To this end, the chemical has traditionally been confined in a thick-walled metal carrier or charged directly into a metal detonator barrel. U.S. Patent 2999460 mentioned above
Although lead or plastic tubing has been proposed for thick-walled charge carriers in It would destroy its integrity and its delayed properties would be nullified. This can be understood from the fact that conventional detonators with plastic cases, such as those described in US Pat. No. 2,767,655, are instantaneous detonators (i.e., detonators without delayed firing). One of the important features of the delayed detonator of the present invention is that the trigger charge does not penetrate into the delay charge, preferably because of the polyolefin or polyfluorocarbon capsule as the delay charge carrier as shown in FIG. This is to take a form that substantially prevents When the carrier capsule is placed over the granular spot explosive, the closed end of the capsule acts as a barrier to prevent particles of the spot explosive from penetrating into the delay charge. It is believed that this separation of the delay charge from the point explosive contributes to the uniformity of the delay time of the detonator of the present invention. Of course, perfect isolation is not practicable since continuity between the columns of the various charges is necessary to ensure the detonation of the point explosive and the charge. As shown in Example 3, even if there is no barrier layer between the time delay charge and the spot charge, the pressing force applied to the charge of the spot charge will cause the carrier tube and the time delay charge to be placed on top of the spot charge. Good uniformity of the delay time can also be obtained if the pressure is sufficient to compact the spot explosive to a degree that prevents displacement of the loose surface of the spot explosive when it is pressed into the detonator barrel. . In particular, if the delay charge carrier is an open tube, the pressing force applied to the spot charge should be at least about 225 Newtons. The time-prolonging drug carrier, capsule 5 in FIG. 1 or tube 20 in FIG. 2, is fabricated by molding or extrusion of polyolefin (eg, polyethylene or polypropylene) or polyfluorocarbon (eg, polytetrafluoroethylene). Such plastic materials are eminently suitable for use in direct contact with exothermic combustible time-prolonging agents in detonators. More specifically, these plastics readily melt when exposed to the heat produced by the combustion of the detonator with which they are in contact, without undergoing gas-generating decomposition that could result in rupture of the detonator barrel. do. For example, in the case of a 350 millisecond delay, any point on the plastic can withstand exposure to a 1 mm flame front (e.g., at a temperature of about 1000 degrees Celsius) for about 35 milliseconds. Must be able to do it. Since the time interval between the application of the ignition impulse and the detonation of the detonator is determined by the burning rate of the delay charge and the length of its tube, a longer delay will result if the composition of the delay charge is constant. A longer delay charge carrier would be required to accommodate the longer delay charge required for the firing time detonator. Therefore, it will be necessary to increase the length of the outer cylinder 1 as well. The diameter of the time delay drug can be varied by varying the wall thickness of the carrier capsule or tube. Therefore, if it is desired to lengthen the delayed onset time by increasing the length of the column (cylindrical body) of the time delay drug with a constant time delay drug composition, the diameter of the time delay drug should be made smaller for all or part of its length. By doing so, it is possible to avoid the total charge amount of the delay charge becoming so large that the detonator barrel cannot withstand it. Without the carrier capsule or tube present in the delayed detonator of the present invention, a longer delay charge column would result in too large a total charge of delay charge, so obtaining a longer delay time would result in less combustion. It may be necessary to use a different composition that is slower, so that the uniformity of the delay time will be worse. Generally, the wall thickness of the carrier wall is about 0.5 mm or more and about 1.7 mm or less, and the diameter of the time delay drug is about 3 mm or more. In the preferred detonator of the present invention, a tubular rigid metal capsule (10 in FIG. 1) having a closed end with an axial orifice at one end is inserted into the capsule or tube of the extended drug carrier in its closed end. The end rests on the delay charge and is preferably nested so that its open end faces the firing end (rather than the detonating end) of the detonator. The metal capsule may be made of bronze, copper or steel, for example, or, if of sufficient thickness, of aluminum. The metal capsule forces the delay charge carrier into tight contact with the primer barrel, helping to hold the delay charge in place and reinforcing the primer barrel against destruction by impact. The composition of the various charges of the detonator is not particularly limited in the present invention as long as the composition fulfills its intended function. The delay agent may be any gas-free exothermic reactive mixture of solid oxidizer/reductant that burns at a constant rate and is conventionally used in ventless delayed detonators. Examples of such mixtures are boron-lead, boron-lead-dibasic lead phosphite, aluminum-cupric oxide, magnesium-barium peroxide-selenium, and silicon-lead. The time delay drug should be pressed into the carrier with a force of at least about 890 Newtons. The trigger explosive may be any heat-sensitive explosive composition that is readily detonated by combustion of the delay charge composition, such as lead azide, mercuric fulmate, diazodinitrophenol, and the like. The composition used as an additive may be any conventional additive, such as PETN, cyclotrimethylenetrinitramine, cyclotetramethylenetetranitramine, lead azide, picrylsulfone, nitromannite, TNT, etc. good. The additive may be in a loosely packed state or compacted. The detonator of the present invention may be electrical or non-electric. A preferred igniter for an electric detonator is shown in FIG. However, US Patent 2771033 and
Other known electrical igniters, such as those shown in US Pat. No. 2,773,447, can also be used to ignite the delay charge. In a non-electric detonator, instead of an electric igniter, the ignition charge is added by means of a detonator, as shown in Figure 2 of U.S. Patent No. 3,021,786 and Figure 2 of Japanese Patent Application No. 55-021,756. An igniter is used which ignites by means of a pressure pulse.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a delayed electric detonator of the present invention in which a time-prolonging drug is housed in a capsule made of polyolefin or polyfluorocarbon; FIG. FIG. 2 is a partial vertical cross-sectional view of the delayed detonator of the present invention. 1... External tube, 2... Loading agent, 3... Point explosive, 4... Time delay drug, 5... Time delay drug capsule, 8... Orifice, 10
... Metal capsule, 13... Orifice, 14... Ignition device, 15... Ignition powder, 16... Leg line, 17... Bridge line,
20... Temporary medicine storage tube body.

Claims (1)

[Scope of Claims] 1. In a tubular metal outer cylinder integrally closed at one end, in order from the closed end side, (a) a charge consisting of an explosive composition, and (b) a heat-sensitive explosive composition. point explosive consisting of
(c) a time delay charge made of an exothermic combustible composition; and (d) a delayed detonator containing an igniter for igniting the time delay charge, wherein the time delay charge and the inner wall of the tubular metal outer cylinder are connected to each other. A delayed detonator characterized in that it is in such a form that the point explosive is substantially prevented from penetrating into the delay charge, with a layer of polyolefin or polyfluorocarbon interposed therebetween. 2. The delayed detonator described in claim 1, in which the interface between the delay charge and the point explosive exists only in a small portion near the central axis of the tubular metal outer cylinder. A barrier layer is present to some extent. 3. The delayed detonator according to claim 2, wherein the barrier layer is made of polyolefin or polyfluorocarbon. 4. The delayed detonator according to claim 3, wherein the delay charge is nested in the tubular metal outer cylinder, with one end opening and the other end penetrating in the axial direction. Encased in a tubular polyolefin or polyfluorocarbon capsule having an orifice closure, the capsule closure being in contact with the point explosive. 5. A delayed detonator according to claim 1, wherein the delay charge is housed in a polyolefin or polyfluorocarbon tube, and the point charge is press-fitted onto the delay charge accommodating tube. Sometimes in a sufficiently compacted form that the drop charge is not disturbed enough to be able to penetrate into the delay charge. 6. A delayed detonator according to claim 4 or 5, wherein the polyolefin or polyfluorocarbon delay drug containing tube or capsule has an axial orifice that is open at one end and penetrated at the other end. A tubular rigid metal capsule having a closure portion provided with a cylindrical tube is nested into the capsule such that the closure portion of the rigid metal capsule is in contact with the time-prolonging drug. 7. A delayed firing cap according to claim 6, wherein the open end of the rigid metal capsule faces an ignition device. 8. The delayed detonator according to claim 4 or 5, wherein the delay drug storage tube or capsule is made of polyethylene and/or polypropylene. 9. The delayed detonator according to claim 4 or 5, wherein the delay drug storage tube or capsule is made of poly(tetrafluoroethylene). 10. The delayed detonator of claim 1, wherein the delay charge is a pressurized granular mixture of boron and red lead containing about 0.5 to 2.5% boron. 11. The delayed detonator according to claim 1, wherein the ignition device contains an igniter that can be ignited by supplying electrical energy. 12. A delayed detonator according to claim 1, wherein the ignition device contains an ignition charge that can be ignited by a pressure pulse applied by a detonating cord.